All CTB score tables I've seen prove to be naive and pretty useless if you consider them critically. The common flaws in those ratings are:
1. No certain protocols are defined for the assessed methods.
You can't assess abstract methods adequately. It's nearly the same as scoring suicide in general. How would you react if someone told you that lethality of a suicide attempt is 10%, the agony level is 50% and time to death is 1 hour (without mentioning any details on how the attempt is done). This would sound ridiculously, right? Your first thought would probably be "such things depend on the method actually".
When you take a closer look at the "methods" presented in those score tables and if you're knowledgeable enough, you can notice that each of them can be done with a great variety of protocols that may give very different outcomes.
2. When talking about agony, the authors do not clearly distinguish the intensity of discomfort and its duration.
Ask yourself, what is worse: experiencing 75%-intense discomfort for 1 second or experiencing 25%-intense discomfort for 1 hour/day/month/year? Different people can prefer different ratios between intensity and duration, so all integral agony scores are inherently highly biased.
And what is 100% agony on the scale that doesn't have an upper bound for the duration at all? Is 100%-intense pain experienced during 5 seconds presumed to be equivalent to 100%-intense pain experienced during 5 minutes, 5 hours, or 5 days?
This page
https://archive.ashspace.org/ashbusstop.org/lta_calc.html tries to take time into consideration, but the suggested method is just nonsensical - it's based on the time to death rather than the duration of conscious state. The numbers presented as time to death also rise lots of questions. According to the site, death from "shotgun to head" takes 1.7 minutes. Are they serious? If the shotgun is powerful enough and the shot is done correctly, you die in less than 0.1 seconds.
3. The notion of "peacefulness" is rather vague. In general, people may combine several different aspects of CTB in this parameter:
- intensity and duration of physical discomfort,
- probable intensity and duration of anxiety or other mental discomfort induced by using the CTB protocol,
- whether the protocol is associated with gore or violence,
- how much the protocol is prone to causing inconveniences, distress, or risks to health/life for other people.
Trying to address so many different things in a single common score inevitably leads to imposing some personal taste, preferences, and bias to others. Attempts to evaluate an overall integer score for a method based on reliability, discomfort, availability, etc doesn't look smart either. It's just playing with numbers, which doesn't have anything common with real science. You can safely multiply the results of such calculations by the unit imaginary number (i) - at least, their practical usefulness would be better reflected then.